Something worth mentioning. If you have the Toxic Wastling pet, any critter it eats counts for the Critter Kill Squad total. So if you don't want to sit and do a dedicated grind on this one, let the Wastling do the work for you! (though it will take a much much much longer time going that rout.)

My favorite pet I have. Kinda view it as my good luck booger, always summoning it whenever I do any dungeon run. Seeing it eat random critters is always worth a giggle. I've seen it eat turkeys, squirrels, mice, rats, penguins, even a cow once.

Also, something new as of Cataclysm. To get the Armadillo Pup pet from the Guild Achievement Critter Kill Squad, you need to have your guild kill 50,000 critters. Any critter that the Toxic Wastling eats counts towards this total. S